Monolithic Power Converter Package with Through Substrate vias

ABSTRACT

According to an exemplary embodiment, a monolithic power converter package includes a monolithic die over a substrate, the monolithic die integrating a driver integrated circuit (IC) with a control power transistor and a sync power transistor connected in a half-bridge. The high side power input and a power output of the half-bridge each are disposed on a top surface of the monolithic die. The high side power input is electrically coupled to the substrate through a high side power connection. The power output is electrically coupled to the substrate through a power output connection. The low side power input of the half-bridge comprises a plurality of through substrate vias that extend through the monolithic die to electrically connect a low side power pad to the monolithic die.

The present application claims the benefit of and priority to a provisional application entitled “Monolithic Power Converter Package with Through Semiconductor Vias,” Ser. No. 61/619,612 filed on Apr. 3, 2012. The disclosure in this provisional application is hereby incorporated fully by reference into the present application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is generally in the field of semiconductors. More particularly, the invention relates to the packaging of semiconductor dies.

2. Background Art

Switch-mode power converters, such as synchronous power converters, are well known. A synchronous power converter may typically include a control power transistor and a synchronous (sync) power transistor connected in a half-bridge and a driver integrated circuit (IC) for driving the control and sync power transistors. It is desirable to form a synchronous power converter in which a control power transistor, a sync power transistor, and a driver IC are monolithically formed on a common die (i.e. a monolithic die). Among other advantages, such a monolithic die would allow for packaging that is smaller and easier to assemble than a synchronous power converter having more than one die.

The monolithic die can have a high side power input, a low side power input, and a power output of the half-bridge. One approach to assembling the monolithic die in a package would be to connect to the high side power input, the low side power input, and the power output using bond wires. However, in order to achieve low resistive and inductive connections for the monolithic die, many bond wires must be attached to the monolithic die. As such, assembling the monolithic die in the package would become complex and costly. Furthermore, bond wires can be prone to lift-off due to, for example, mechanical stress that can cause the bond wires to fail. Additionally, bond wires can interfere with placement of a heat sink to dissipate heat from the monolithic die.

It would be desirable to provide for a monolithic die in a power converter package that can achieve low resistive and inductive connections for the monolithic die by reducing or eliminating use of bond wires for connection to a high side power input, a low side power input, and a power output of the monolithic die.

SUMMARY OF THE INVENTION

A monolithic power converter package with through substrate vias, substantially as shown in and/or described in connection with at least one of the figures, and as set forth more completely in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary circuit schematic of a monolithic power converter package, according to one embodiment of the invention.

FIG. 2A illustrates a top view of a monolithic power converter package, according to one embodiment of the present invention.

FIG. 2B illustrates a selective top view of a monolithic power converter package, according to one embodiment of the present invention.

FIG. 2C illustrates a perspective view of a monolithic power converter package, according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a monolithic power converter package with through substrate vias. The following description contains specific information pertaining to the implementation of the present invention. One skilled in the art will recognize that the present invention may be implemented in a manner different from that specifically discussed in the present application. Moreover, some of the specific details of the invention are not discussed in order to not obscure the invention. The specific details not described in the present application are within the knowledge of a person of ordinary skill in the art.

The drawings in the present application and their accompanying detailed description are directed to merely exemplary embodiments of the invention. To maintain brevity, other embodiments of the invention that use the principles of the present invention are not specifically described in the present application and are not specifically illustrated by the present drawings.

FIG. 1 shows an exemplary schematic of monolithic power converter package circuit 100 (also referred to as “power converter circuit”), according to one embodiment of the invention. In the present embodiment, power converter circuit 100 includes half-bridge 106 comprising high side power transistor 102 a (also referred to as “control power transistor”) and low side power transistor 102 b (also referred to as “synchronous (sync) power transistor”). Also in the present embodiment, power converter circuit 100 includes high side power input terminal V_(H), low side power input terminal V_(L), IC input terminals IC_(in1), IC_(in2), IC_(in3), and IC_(in4), and power output terminal V_(out).

Half-bridge 106 includes high side power input 118, low side power input 126, and power output 120. High side power input 118 is coupled to high side power input terminal V_(H), low side power input 126 is coupled to low side power input terminal V_(L), and power output terminal 120 is coupled to power output terminal V_(out). In the present embodiment, low side power input 126 is a ground input for half-bridge 106 while high side power input 118 b is a high voltage input.

Control power transistor 102 a and sync power transistor 102 b of half-bridge 106 can be respective control and sync power transistors of a switched-mode power converter, such as a synchronous power converter (e.g., a synchronous buck converter). Control power transistor 102 a and sync power transistor 102 b can generally be any transistor, such as a field-effect transistors (FET). Non-limiting examples of control power transistor 102 a and sync power transistor 102 b include a metal-oxide-semiconductor field-effect transistor (MOSFET), a high electron mobility transistor (HEMT), an insulated gate bipolar transistor (IGBT), and the like.

As shown in FIG. 1, control power transistor 102 a has source S₁, drain D₁, and gate G₁ whereas sync power transistor 102 b has source S₂, drain D₂, and gate G₂. Control power transistor 102 a is coupled between high side power input terminal V_(H) and power output terminal V_(out). Sync power transistor 102 b is coupled between power output terminal V_(out) and low side power terminal V_(L). High side power input terminal V_(H) is for receiving a high side power input and low side power input terminal V_(L) is for receiving a low side power input, such as ground.

Monolithic power converter package circuit 100 can include additional components that are not specifically shown in FIG. 1. For example, in some embodiments control power transistor 102 a can have a diode coupled to source S₁ and drain D₁. In one embodiment, for example, a freewheeling diode is antiparallel with control power transistor 102 a. Similarly, sync power transistor 102 b can have a diode coupled to source S₂ and drain D₂, which can be a freewheeling diode that is antiparallel with sync power transistor 102 b.

Half bridge 106 is coupled to driver integrated circuit (IC) 104, which is for driving control power transistor 102 a and sync power transistor 102 b to generate power output signal VO for power output terminal V_(out). In the present embodiment driver IC 104 has four IC inputs 122 a, 122 b, 122 c, and 122 d coupled respectively to IC input terminals IC_(in1), IC_(in2), IC_(in3), and IC_(in4). In various embodiments of the present invention, IC inputs terminals IC_(in1), IC_(in2), IC_(in3), and IC_(in4) can receive any suitable inputs for a driver IC. Examples include a feedback signal, such as a signal generated from power output 120, a power input for powering driver IC 104, and a gate control signal for control power transistor 102 a and/or sync power transistor 102 b. While the present embodiment includes four IC input terminals IC_(in1), IC_(in2), IC_(in3), and IC_(in4) and four IC inputs 122 a, 122 b, 122 c, and 122 d, other embodiments have more or fewer IC input terminals and IC inputs.

Also in the present embodiment, driver IC 104 provides high side signal HO to gate G₁ of control power transistor 102 a to drive control power transistor 102 a and provides low side signal LO to gate G₂ of sync power transistor 102 b to drive sync power transistor 102 b. More particularly, high side signal HO and low side signal LO can be utilized to selectively enable and disable control power transistor 102 a and sync power transistor 102 b.

Referring now to FIGS. 2A-2C, FIGS. 2A-2C illustrate different views of monolithic power converter package 200 (also referred to as “power converter package”), according to one embodiment of the present invention. FIG. 2A illustrates a top view of power converter package 200, FIG. 2B illustrates a selective top view of power converter package 200, and FIG. 2C illustrates a perspective view of power converter package 200. Monolithic power converter package 200 in FIGS. 2A-2C corresponds to monolithic power converter package circuit 100 in FIG. 1.

In the present embodiment, monolithic power converter package 200 is a synchronous buck converter package comprising monolithic die 208, substrate 210, high side power connection 212 a, power output connection 212 b, and bond wires 214 a, 214 b, 214 c, and 214 d.

In monolithic power converter package 200, substrate 210 comprises any suitable substrate. Examples of substrate 210 include a ceramic substrate, a printed circuit board (PCB) substrate, a laminate substrate, a direct bonded copper (DBC) substrate, and a leadframe. In the present embodiment, substrate 210 includes high side power pad 216 a, low side power pad 216 b, power output pad 216 c, and IC pads 216 d, 216 e, 216 f, and 216 g, which comprise conductive material, such as copper. Also in the present embodiment, high side power pad 216 a, low side power pad 216 b, power output pad 216 c, and IC pads 216 d, 216 e, 216 f, and 216 g correspond respectively to high side power input terminal V_(H), low side power input terminal V_(L), power output terminal V_(out), and IC input terminals IC_(in1), IC_(in2), IC_(in3), and IC_(in4) in FIG. 1.

As shown in FIGS. 2A-2C, monolithic die 208 is over substrate 210. More particularly, monolithic die 208 is over low side power pad 216 b of substrate 210. Monolithic die 208, comprises driver IC 204, corresponding to driver IC 104 in FIG. 1 and half-bridge 206, corresponding to half-bridge 106 in FIG. 1. Thus, monolithic die 208 is integrating driver IC 204 with a control power transistor, corresponding control power transistor 102 a in FIG. 1, and a sync power transistor, corresponding to sync power transistor 102 b in FIG. 1, where the control power transistor and the sync power transistor are connected in half-bridge 206. In FIGS. 2A-2C, a dashed line indicates a separation between driver IC 204 and half-bridge 206.

Monolithic die 208 further comprises high side power input 218, low side power input 226 (also referred to as “through substrate vias”), power output 220, and IC inputs 222 a, 222 b, 222 c, and 222 d, which correspond respectively to high side power input 118, low side power input 126, power output 120, and IC inputs 122 a, 122 b, 122 c, and 122 d in FIG. 1. FIG. 2B illustrates a selective top view of monolithic power converter package 200 that does not show high side power connection 212 a and power output connection 212 b in order more clearly show high side power input 218 and power output 220 of half-bridge 206 each being disposed on top surface 230 of monolithic die 208. FIGS. 2A-2C further show that IC inputs 222 a, 222 b, 222 c, and 222 d (also referred to as “plurality of IC inputs 222 a-222 d”) of driver IC 204 are each disposed on top surface 230 of monolithic die 208.

In the present embodiment, plurality of IC inputs 222 a-222 d are each electrically and mechanically coupled to said substrate 210. IC input 222 a is electrically and mechanically coupled to substrate 210 by bond wire 214 a. For example, in the present embodiment, bond wire 214 a electrically and mechanically couples IC input 222 a to IC pad 216 d of substrate 210. Furthermore, IC input 222 b is electrically and mechanically coupled to substrate 210 by bond wire 214 b. For example, in the present embodiment, bond wire 214 b electrically and mechanically couples IC input 222 b to IC pad 216 e of substrate 210. Additionally, IC input 222 c is electrically and mechanically coupled to substrate 210 by bond wire 214 c. For example, in the present embodiment, bond wire 214 c electrically and mechanically couples IC input 222 c to IC pad 216 f of substrate 210. Similarly, IC input 222 d is electrically and mechanically coupled to substrate 210 by bond wire 214 d. For example, in the present embodiment, bond wire 214 d electrically and mechanically couples IC input 222 d to IC pad 216 g of substrate 210.

One approach to assembling monolithic die 208 in power converter package 200 would be to connect to high side power input 218, low side power input 226, and power output 220 using bond wires. For example, high side power input 218, low side power input 226, and power output 220 may all be disposed on top surface 230 of monolithic die 208 and have bond wires attached thereto. However, in order to achieve low resistive and inductive connections for monolithic die 208, many bond wires must be attached to monolithic die 208. As such, assembling monolithic die 208 in monolithic power converter package 200 would become complex and costly. Furthermore, bond wires can be prone to lift-off due to, for example, mechanical stress that can cause the bond wires to fail. Additionally, bond wires would interfere with placement of a heat sink over monolithic die 208 to dissipate heat from monolithic die 208.

In accordance with embodiments of the present invention, low side power input 226 comprises a plurality of through substrate vias, such as through substrate vias 226 a, 226 b, and 226 c (shown in FIGS. 2B and 2C), that extend through monolithic die 208 to electrically connect low side power pad 216 b to monolithic die 208. Monolithic power converter package 200 thereby achieves low resistive and inductive connections for monolithic die 208, without using a bond wire for connection to low side power input 226. As such, use of bond wires for connection to high side power input 218, low side power input 226, and power output 220 of monolithic die 208 can be reduced or eliminated. Thus, assembling monolithic die 208 in monolithic power converter package 200 can be accomplished with reduced complexity and cost. Furthermore, through substrate vias 226 are less prone to failure than bond wires and do not interfere with the placement of a heat sink over monolithic die 208 to dissipate heat from monolithic die 208.

FIGS. 2B and 2C illustrate respective top and side views of through substrate vias 226. In FIGS. 2B and 2C, through substrate vias 226 are indicated using a dashed outline, as they would not otherwise be visible. Through substrate vias 226 are under high side power input 218, power output 220, and top surface 230 of monolithic die 208. As shown in FIG. 2B, in the present embodiment, through substrate vias 226 are arranged in at least one array within monolithic die 208. Also in the present embodiment, through substrate vias 226 are distributed throughout half-bridge 206 of monolithic die 208 and are not within driver IC 204. However, through substrate vias 226 can have many different arrangements and configurations and can be electrically connected to at least one metallization layer within monolithic die 208. Furthermore, in the present embodiment, through substrate vias 226 have a cylindrical shape, however, through substrate vias 226 can have any suitable shape and size.

As described above, one approach to assembling monolithic die 208 in power converter package 200 would be to connect to high side power input 218, low side power input 226, and power output 220 using bond wires where high side power input 218, low side power input 226, and power output 220 may all be disposed on top surface 230 of monolithic die 208 and have bond wires attached thereto. However, in the present embodiment, low side power input 226 is not on top surface 230 of monolithic die 208. As such, high side power input 218 and power output 220 can occupy a larger area on top surface 230 of monolithic die 208. Through substrate vias 226 extending through monolithic die 208 to electrically connect low side power pad 216 b to monolithic die 208 thereby increases a contact area for high side power input 218 and power output 220 on top surface 230 of monolithic die 208. As such, high side power input 218 and power output 220 can have lower contact resistance and increased current carrying capability.

In the present embodiment, high side power input 218 is electrically and mechanically coupled to substrate 210 by high side power connection 212 a. For example, in the present embodiment, high side power connection 212 a electrically and mechanically couples high side power input 218 to high side power pad 216 a of substrate 210. Furthermore, power output 220 is electrically and mechanically coupled to power output pad 216 c of substrate 210 by power output connection 212 b. For example, in the present embodiment, power output connection 212 b electrically and mechanically couples power output 220 to power output pad 216 c of substrate 210. FIGS. 2A and 2C show that power output connection 212 b overhangs side 224 a of monolithic die 208 and high side power connection 212 a overhangs side 224 b of monolithic die 208, which is opposite side 224 a. Using such an arrangement, power output connection 212 b and high side power connection 212 a can be large with high current carrying capability. In the present embodiment power output connection 212 b and high side power connection 212 a are of approximately a same size.

In some embodiments, high side power connection 212 a comprises at least one bond wire. Power output connection 212 b can also comprise at least one bond wire in embodiments of the present invention. However, in some embodiments, at least one of high side power connection 212 a and power output connection 212 b comprises a power strip. For example, in the present embodiment, high side power connection 212 a is a high side power strip and power output connection 212 b is a power output strip, as shown in FIGS. 2A and 2C. Thus, in the present embodiment, monolithic power converter package 208 thereby achieves low resistive and inductive connections for monolithic die 208, without using a bond wire for connection to high side power input 218, low side power input 226, and power output 220.

One example of a power strip is a conductive clip, such as a copper clip. Thus, in some embodiments, high side power connection 212 a comprises a high side power clip and power output connection 212 b comprises a power output clip. In embodiments where at least one of high side power connection 212 a and power output connection 212 b comprises a conductive clip, the conductive clip can be, for example, soldered to at least one of high side power input 218 and power output 220, as well as be soldered to a corresponding one of high side power pad 216 a and power output pad 216 c. Furthermore, in such embodiments, at least one of high side power input 218 and power output 220 can comprise a solderable front metal (SFM).

Another example of a power strip is a conductive ribbon. Thus, in some embodiments, high side power connection 212 a comprises a high side power ribbon and power output connection 212 b comprises a power output ribbon. The conductive ribbon can be, as examples, an aluminum ribbon, a copper ribbon, and an aluminum or copper clad ribbon. In embodiments where at least one of high side power connection 212 a and power output connection 212 b comprises a conductive ribbon, the conductive ribbon can be, for example, mechanically bonded to at least one of high side power input 218 and power output 220, as well as being mechanically bonded to a corresponding one of high side power pad 216 a and power output pad 216 c. The mechanical bonding can be facilitated by, for example, ultrasonic vibrations.

In accordance with embodiments of the present invention, high side power connection 212 a, low side power strip 212 b, and power output connection 212 b can comprise any combination of a conductive clip, a conductive ribbon, and another power strips not specifically described herein. Furthermore, monolithic power converter package 200 can comprise more than one of high side power strip and more than one power output strip.

A high side power strip and power output strip each have lower resistivity and inductance than a bond wire. As such, less high side power strips and power output strips are required as compared to bond wires to achieve low resistive and inductive connections for monolithic die 208. For example, the embodiment shown in FIGS. 2A-2C includes only one high side power connection 212 a and only one power output connection 212 b. As such, assembling monolithic die 208 in monolithic power converter package 200 can be accomplished with further reduced complexity and cost. Furthermore, high side power connection 212 a and power output connection 212 b are less prone to failure than bond wires. Additionally, high side power connection 212 a and power output connection 212 b could accommodate a heat sink over monolithic die 208 to dissipate heat from monolithic die 208.

Thus, as discussed above with respect to FIGS. 1, 2A, 2B, and 2C, embodiments of the present invention can provide for a monolithic die in a power converter package that can achieve low resistive and inductive connections for the monolithic die, by reducing or eliminating use of bond wires for connection to a high side power input, a low side power input, and a power output of the monolithic die. More particularly, in various embodiments, a low side power input of a half-bridge comprises a plurality of through substrate vias that extend through the monolithic die to electrically connect a low side power pad to the monolithic die. The monolithic power converter package can thereby achieve low resistive and inductive connections for the monolithic die, without using a bond wire for connection to the low side power input.

From the above description of the invention it is manifest that various techniques can be used for implementing the concepts of the present invention without departing from its scope. Moreover, while the invention has been described with specific reference to certain embodiments, a person of ordinary skill in the art would appreciate that changes can be made in form and detail without departing from the spirit and the scope of the invention. Thus, the described embodiments are to be considered in all respects as illustrative and not restrictive. It should also be understood that the invention is not limited to the particular embodiments described herein but is capable of many rearrangements, modifications, and substitutions without departing from the scope of the invention. 

The invention claimed is:
 1. A monolithic power converter package comprising: a monolithic die over a substrate, said monolithic die integrating a driver integrated circuit (IC) with a control power transistor and a sync power transistor connected in a half-bridge; a high side power input and a power output of said half-bridge each being disposed on a top surface of said monolithic die; said high side power input being electrically coupled to said substrate through a high side power connection; said power output being electrically coupled to said substrate through a power output connection; a low side power input of said half-bridge comprising a plurality of through substrate vias that extend through said monolithic die to electrically connect a low side power pad to said monolithic die; said monolithic power converter package thereby achieving low resistive and inductive connections for said monolithic die, without using a bond wire for connection to said low side power input.
 2. The monolithic power converter package of claim 1, wherein said a plurality of through substrate vias are arranged in at least one array within said monolithic die.
 3. The monolithic power converter package of claim 1, wherein said plurality of through substrate vias extending through said monolithic die to electrically connect said low side power pad to said monolithic die thereby increase a contact area for said high side power input and said power output on said top surface of said monolithic die.
 4. The monolithic power converter package of claim 1, wherein said monolithic power converter package also achieves low resistive and inductive connections for said monolithic die, without using a bond wire for connection to said high side power input and said power output.
 5. The monolithic power converter package of claim 1, wherein said power output connection electrically and mechanically couples said power output to a power output pad of said substrate.
 6. The monolithic power converter package of claim 1, wherein said high side power connection electrically and mechanically couples said high side power input to a high side power pad of said substrate.
 7. The monolithic power converter package of claim 1, wherein said monolithic die is over said low side power pad.
 8. The monolithic power converter package of claim 1, wherein said power output connection overhangs one side of said monolithic die and said high side power connection overhangs another side of said monolithic die.
 9. The monolithic power converter package of claim 1, wherein said low side power input is a ground input for said half-bridge.
 10. The monolithic power converter package of claim 1, wherein said high side power input is electrically and mechanically coupled to said substrate by only one high side power connection.
 11. The monolithic power converter package of claim 1, wherein said power output is electrically and mechanically coupled to said substrate by only one power output connection.
 12. The monolithic power converter package of claim 1, wherein said high side power connection is a high side power strip.
 13. The monolithic power converter package of claim 1, wherein said power output connection is a power output strip.
 14. The monolithic power converter package of claim 1, wherein said high side power connection is a high side power clip.
 15. The monolithic power converter package of claim 1, wherein said power output connection is a power output clip.
 16. The monolithic power converter package of claim 1, wherein said monolithic power converter package is a synchronous buck converter package.
 17. The monolithic power converter package of claim 1, further comprising a plurality of IC inputs disposed on said top surface of said monolithic die.
 18. The monolithic power converter package of claim 1, further comprising a plurality of IC inputs disposed on said top surface of said monolithic die, said plurality of IC inputs each being electrically and mechanically coupled to said substrate. 